N:dlzc D:aol T:com (dlzc) wrote:

"Martin Brown" wrote in
message ...

N:dlzc D:aol T:com (dlzc) wrote:

Dear Martin Brown:

"Martin Brown" wrote in
message ...

N:dlzc D:aol T:com (dlzc) wrote:

Yes, trick needed. Schwarzchild is singular at the event
horizon, as we have covered ad nauseum. Yet he managed to
achieve a continuous presentation... maybe it is well behaved
on either side of the EH.

Schwarzschild coordinates are singular at the event horizon in
the same way that latitude and longitude are singular at the
Earth's North pole.

Which of those goes to infinity, Martin?

Neither. But some infinities can be dealt with safely.

Similar predictions are made in Kruskal and Eddington models, and
they are not singular at the EH. We simply don't know what he
used.

I don't believe the choice of coordinate systems makes any difference to
the physics - it is just more confusing and difficult to work out the
calculations in some than in others.

It doesn't have any real physical significance and can be
worked
around.

Kruskal, Eddington and others. Yes, I know.

Then why do you choose to ignore them?

Why do you assume that I did? They both fold outer space or
outer spacetime into a separate inner time axis. Why do you
posture, rather than read the references that have been cited?

I must have missed the references you cited in support of your position.
Please repost them...

I
understand this is uncomfortable, and I am sorry for that. It is
just a question. Teenagers ask about sex too...

You are begining to sound like Gerald Kelleher.

The singularity at the centre of a BH in the classical GR
geometric interpretation cannot be so easily dismissed.

Yes, it can. "Classical GR" provides that an entirely
separate Universe is formed inside the BH. And if this is
close to reality, the "central singularity" we are heading for
(but will never reach) is an infinitely diffuse, cold future.
"Newton" provides a "central infinitely dense lump at the
center."

I think you will find most practitioners expect infalling
material to find itself at the centre of a BH (even a large
one) in a relatively short time. ISTR an hour or so for a big
galactic centre BH.

Outer expectations of inner duration are simply the Newton in you
(and others). Once the object crosses the event horizon, it is
gestalt with the BH. If somone wanted a "speed of gravity"
experiment, that would be the place to run it. When would an
orbitting body cease to respond to two distinct bodies, and only
orbit the single fatter BH?

I am inclined to trust the dynamical equations YMMV.

The analogies are fine George. Unfortunately, *to whom* does
the infalling person appear to fall at c?

Himself.

That is going to take some explaining. Light can and will
pass him at c in both directions (towards and away from EH).
So which way does he get "infintely redshifted light", and
from which way does he get "infintely blueshifted light"?
Just because light does not exit the EH, doesn't mean that
light cannot be directed opposite his fall.

Lets try the more precise description for a massive test
particle falling under GR of "c-epsilon" as epsilon tends to
zero instead.

So he doesn't fall at c wrt himself, and you are busting my
chops. Great!

He can measure his own velocity wrt to the fixed stars located outside
the black hole and provided he chooses a nice massive queiecent BH to
jump into he might live long enough to complete the experiment before
being annihilated on reaching the centre.

And he can still see the fixed stars outside the BH.

That is what Andrew's simulations show, yes. Yet the photon
sphere will be continually ingested/drained by an expanding
hole, and the Einstein rings will sucessively give up some of
their contents. At least.

Sorry but I cannot make any sense of the last two sentences.
You won't be able to see anything out of an active feeding BH
since it will be surrounded by opaque dense relativistic
plasma.

WE
ARE
TALKING
ABOUT
A
FALLING
PERSON
INSIDE.

Definitely strong indications of NetKook here. Shouting incoherently.

How is the world is he supposed to see specular images through an
opaque dense relativistic plasma (shades of the CMBRM, Batman!),
Martin? Can we see through the CMBRM?

A BH in total isolation from all other matter is only detectable from
outside by watching how it distorts light passing near it. Only when it
is actively feeding is there an accretion disk, relativistic plasmas
etc. Light from outside can cross and enter freely through the EH, but
it can never leave (shades of Hotel California).

In practice I suspect there may be some opacity problems near real ones
that are not feeding because of rotating embedded magnetic fields and
electron positron pair production etc. Maybe someone has done the
calculation. But in a thought experiment the requirement is only to
decide whether the existing laws of physics can be applied to the
situation and yield a self consistent result.

The falling observer is entitled to enter the BH with a clock
and full knowledge of the laws of astronomy, physics and
GR. He can measure the mass/size of the BH and then
time how long it takes him to reach the singularity
(subject to some minor experimental difficulties).

Sure can. Apparently ~125 Gy give or take tens (or hundreds)
of Gy.

Is that an estimate of the time to reach our nearest BH ? Or
something else? Most estimates I have seen for observers time
to live after freefalling into even the most massive BH
observed in our universe are only a couple of hours.

That is the *internal* time it takes for us to reach the
"infinitely diffuse cold, future". People that think Newton,
standing on the outside, will see us "undifferentiate" the
instant they figure we cross the event horizon. The horizon is
the "singularity at the center" to those "outsiders".

Or not. That is what the question is about.

You are really going to have to define your terms more carefully and/or
draw what you mean or better still the equations. Once again your last
few sentences do not make any sense to me.

I don't think we are using much Newtonian dynamics here...

Regards,
Martin Brown